1. Field of the Invention
The present invention relates to an engine control device capable of controlling an internal combustion engine to start by a starter.
2. Description of the Related Art
In general, an internal combustion engine mounted to a vehicle starts to rotate when a starter drives the crank shaft of the internal combustion engine, namely, the starter provides an initial rotation power to the crank shaft of the internal combustion engine. Specifically, a pinion fixed to the starter is pushed toward an axial direction of a rotary shaft of the pinion gear in order to mesh or engage the pinion with a ring gear which is fixed to the crank shaft of the engine. After this, when receiving an electric power, a starter motor of the starter starts to rotate. The rotation of the starter motor is transmitted to the ring gear, and the cranking operation of the internal combustion engine starts. The internal combustion engine thereby starts to rotate.
There is a conventional technique disclosed in Japanese patent laid open publication No. JP 2006-242082. Such a conventional technique adjusts the stop position of a piston in the corresponding cylinder (as a combustion chamber) of an internal combustion engine when the internal combustion engine is stopped. That is, the conventional technique controls the stop position of the piston at a desired position in the corresponding cylinder. After this, the conventional technique instructs the internal combustion engine to restart on receiving a request to restart the internal combustion engine.
However, the above conventional technique performing the stop position control of the piston involves a drawback that the stop piston of the piston has approximately the same stop position in the corresponding cylinder when the internal combustion engine is stopped, and the ring gear and the pinion become in mesh at approximately the same position, and abrasion occurs at the same mesh portion of the ring gear, that is, abrasion is concentrated at the same mesh portion of the teeth of the ring gear. The advance of abrasion often causes incorrect mesh state between the ring gear and the pinion. This would often cause unsmoothed starting of the internal combustion engine.
On the other hand, the above conventional drawback is also generated in a case without performing any stop position control. That is, the above conventional drawback also occurs when the rotation of the internal combustion engine is stopped without performing any stop position control because the piston in the cylinder under the compression stroke cannot travel over the top dead center (TDC) by the presence of a compression load of the cylinder in the compression stroke. As a result, because the piston is slightly returned toward the direction away from the TDC in the compression stroke, the piston always stops at approximately the same position in the cylinder in the compression stroke even if the stop position control is not performed.
Accordingly, when the internal combustion engine is stopped without performing any stop position control, it would also occur the above conventional drawback to advance abrasion of a specified portion of the teeth of the ring gear, like the above case which performs the stop position control.